amxmodx/public/sm_stringhashmap.h

/**
 * vim: set ts=4 sw=4 tw=99 noet :
 * =============================================================================
 * SourceMod
 * Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.
 * =============================================================================
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, version 3.0, as published by the
 * Free Software Foundation.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * As a special exception, AlliedModders LLC gives you permission to link the
 * code of this program (as well as its derivative works) to "Half-Life 2," the
 * "Source Engine," the "SourcePawn JIT," and any Game MODs that run on software
 * by the Valve Corporation.  You must obey the GNU General Public License in
 * all respects for all other code used.  Additionally, AlliedModders LLC grants
 * this exception to all derivative works.  AlliedModders LLC defines further
 * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
 * or <http://www.sourcemod.net/license.php>.
 *
 * Version: $Id$
 */

#ifndef _include_sourcemod_hashtable_h_
#define _include_sourcemod_hashtable_h_

/**
 * @file sm_stringhashmap.h
 *
 * @brief Generic Key -> Value map class, based on a hash table. The Key, in
 * this case, is always an ASCII string, and the value type is a template
 * parameter. This class is intended as a drop-in replacement for KTrie
 * (though the retrieve() signature has been improved).
 *
 * If your Value type already contains the key string, consider using
 * NameHashSet instead.
 */

#include <am-allocator-policies.h>
#include <am-hashmap.h>
#include <am-string.h>
#include <am-moveable.h>
#include <string.h>

namespace SourceMod
{

namespace detail
{
	class CharsAndLength
	{
	 public:
	  CharsAndLength(const char *str)
		: str_(str),
		  length_(0)
	  {
		  int c;
		  uint32_t hash = 0;
		  while ((c = *str++))
			  hash = c + (hash << 6) + (hash << 16) - hash;
		  hash_ = hash;
		  length_ = str - str_ - 1;
	  }

	  uint32_t hash() const {
		  return hash_;
	  }
	  const char *chars() const {
		  return str_;
	  }
	  size_t length() const {
		  return length_;
	  }

	 private:
	  const char *str_;
	  size_t length_;
	  uint32_t hash_;
	};

	struct StringHashMapPolicy
	{
		static inline bool matches(const CharsAndLength &lookup, const ke::AString &key) {
			return lookup.length() == key.length() &&
				   memcmp(lookup.chars(), key.chars(), key.length()) == 0;
		}
		static inline uint32_t hash(const CharsAndLength &key) {
			return key.hash();
		}
	};
}

template <typename T>
class StringHashMap
{
	typedef detail::CharsAndLength CharsAndLength;
	typedef ke::HashMap<ke::AString, T, detail::StringHashMapPolicy> Internal;

public:
	StringHashMap()
		: internal_(ke::SystemAllocatorPolicy()),
		  memory_used_(0)
	{
		if (!internal_.init())
			internal_.reportOutOfMemory();
	}

	typedef typename Internal::Result Result;
	typedef typename Internal::Insert Insert;
	typedef typename Internal::iterator iterator;

	// Some KTrie-like helper functions.
	bool retrieve(const char *aKey, T *aResult = NULL)
	{
		CharsAndLength key(aKey);
		Result r = internal_.find(key);
		if (!r.found())
			return false;
		if (aResult)
			*aResult = r->value;
		return true;
	}

	Result find(const char *aKey)
	{
		CharsAndLength key(aKey);
		return internal_.find(key);
	}

	bool contains(const char *aKey)
	{
		CharsAndLength key(aKey);
		Result r = internal_.find(key);
		return r.found();
	}

	bool replace(const char *aKey, const T &value)
	{
		CharsAndLength key(aKey);
		Insert i = internal_.findForAdd(key);
		if (!i.found())
		{
			memory_used_ += key.length() + 1;
			if (!internal_.add(i))
				return false;
			i->key = aKey;
		}
		i->value = value;
		return true;
	}

	bool insert(const char *aKey, const T &value)
	{
		CharsAndLength key(aKey);
		Insert i = internal_.findForAdd(key);
		if (i.found())
			return false;
		if (!internal_.add(i))
			return false;
		memory_used_ += key.length() + 1;
		i->key = aKey;
		i->value = value;
		return true;
	}

	bool remove(const char *aKey)
	{
		CharsAndLength key(aKey);
		Result r = internal_.find(key);
		if (!r.found())
			return false;
		memory_used_ -= key.length() + 1;
		internal_.remove(r);
		return true;
	}

	void remove(Result &r)
	{
		internal_.remove(r);
	}

	void clear()
	{
		internal_.clear();
	}

	iterator iter()
	{
		return internal_.iter();
	}

	size_t mem_usage() const
	{
		return internal_.estimateMemoryUse() + memory_used_;
	}

	size_t elements() const
	{
		return internal_.elements();
	}


	Insert findForAdd(const char *aKey)
	{
		CharsAndLength key(aKey);
		return internal_.findForAdd(key);
	}

	// Note that |i->key| must be set after calling this, and the key must
	// be the same as used with findForAdd(). It is best to avoid these two
	// functions as the combined variants above are safer.
	bool add(Insert &i)
	{
		return internal_.add(i);
	}

	// Only value needs to be set after.
	bool add(Insert &i, const char *aKey)
	{
		if (!internal_.add(i))
			return false;
		i->key = aKey;
		return true;
	}

private:
	Internal internal_;
	size_t memory_used_;
};

}

#endif // _include_sourcemod_hashtable_h_